This subproject takes full advantage of the opportunities for cross-study comparison of longitudinal studies in an international context to better understand lifespan contextual influences on later life cognitive and physical functioning. Our focus is on social determinants of individual differences In cognition and health, with emphasis on differential aging risk and exposure processes that affect physical and cognitive ability, cognitive reserve, and cognitive decline. However, because many argue that social factors do not affect age- related physical or cognitive outcomes, but rather select upon them, we will use counterfactual approaches, such as propensity score matching, in addition to standard analytic methods, including multi-level models, to Isolate the effects that socio-demographic processes play In cognition and physical functioning in later life. An important aspect of this project is replication and cross-study comparison of results across studies that differ in birth cohort, resources, geography, and culture. Therefore, this subproject will work closely with Core B to develop and utilize an international contextual database when evaluating results to help contextualize our results in a historically sensitive, comparative and rigorous meta-analytic framework. We will examine the competing and complementary effects of educational attainment, socioeconomic status, and childhood cognition on cognition in later life, and evaluate the role of social and contextual changes across successive birth cohorts. In addition, we will evaluate the Impact of work-related demands, age of retirement, and social class on subsequent level and change in cognitive and physical functioning. The subproject will emphasize inter-cohort and cross-national data analysis to provide results that are broadly generalizable and not subject to biases from small samples or particular contexts, permitting Interpretation of cross-study results In a sociohistorical context.